A process to produce dried singulated cellulose pulp fibers is described in U.S. application Ser. No. 09/998,143 (hereinafter the '143 application), filed on Oct. 30, 2001, which is incorporated herein by reference in its entirety, and is assigned to the assignee of the present application. A representative schematic illustration of the process of the '143 application is provided herein as FIG. 8. One process described in the '143 application which is depicted in FIG. 8, uses a rotary airlock 60 interposed between a jet dryer 20 and the pulp feed system. The rotary airlock 60 comprises a single rotor with vanes.
However, it has been determined that the airlock described in the '143 application negatively affected the operation of the jet dryer, resulting in pulp fibers of uneven moisture content and high sonic knots. Furthermore, production capacity was limited as a result of the airlock. It has also been determined that the jet dryer described in the '143 application runs most efficiently when pulp mass flow, pulp particle size, and pulp moisture content are controlled within certain parameters, which the rotary airlock was unable to accomplish. The rotary airlock was incapable of metering pulp to the degree necessary to produce an even mass flow rate of feed pulp to the dryer. The problem with the rotary airlock was that there were unequal volumes of pulp in the cavities between vanes, which caused the dryer to oscillate or “pulse” because of the timed deposits of the unequal volumes introduced into the dryer loop. The pulp came in bundled amounts; therefore, the moisture content of the pulp was unevenly distributed throughout each bundle. The air lock cavities between the vanes were too small and would fill up, causing the rotor to jam due to the pulp bundles being caught between the rotor vane and the rotor housing. Furthermore, the use of the airlock would cause the dryer to surge, thereby also contributing to the fibers having unacceptable varying moisture content. Accordingly, there is a need to provide for an improved method and apparatus to feed a jet dryer. The present invention overcomes the problems with the rotary airlock and has further related advantages.